Display apparatuses to display images are classified into a liquid crystal display employing liquid crystal, a field emission display, a plasma display panel using the discharge of inert gas, and an organic light emitting diode display employing an organic light emitting diode.
Among them, the plasma display panel is applied to only a large-size TV. Meanwhile, the liquid crystal display and the organic light emitting diode display have been applied to various fields from small devices to large devices, such as cellular phones, portable computers, monitors, and TVs.
The liquid crystal display employs electrical and optical characteristics of the liquid crystal.
In detail, the liquid crystal has an anisotropic property in which property values such as values of a refractive index or a dielectric constant are different from each other according to long and short axes of molecules, so that the molecular alignment and an optical property can be easily adjusted.
In other words, the liquid crystal display adjusts light transmittance by changing the alignment of liquid crystal molecules according to the electric field to display images.
In detail, the liquid crystal display displays images through a liquid crystal display panel in which a plurality of pixels are arranged in the form of a matrix.
Each pixel of the liquid crystal display panel represents a desired color through the combination of red, green, and blue sub-pixels by adjusting light transmittance through the change of liquid crystal alignment according data signals.
Each sub-pixel is charged with a differential voltage between a data signal supplied to a pixel electrode through a thin film transistor and a common voltage supplied to a common electrode to drive the liquid crystal.
In addition, the liquid crystal display panel requires a backlight unit to supply a light to a rear surface of the liquid crystal display panel since the liquid crystal display panel is a non-emissive device.
However, the liquid crystal display panel cannot display different images through one screen without interference therebetween.